Shock-absorbing steering assembly
1. Field of the Invention
The present invention relates to a shock-absorbing steering assembly mounted to a vehicle, such as an automobile, for absorbing an impact of a secondary collision between a driver and a steering wheel in an automobile collision.
2. Description of the Prior Art
There have been proposed a variety of shock-absorbing steering column assemblies for absorbing the impact of the secondary collision between the driver and the steering wheel in the automobile collision (see, for example, Japanese Unexamined Patent Publication Nos.5-105088(1993) and 6-329032(1994)). Unfortunately, the conventional shock-absorbing steering column assemblies share a common problem that a shock-absorbing structure is constructed from a large number of elements.
In view of the foregoing, it is an object of the present invention to provide a shock-absorbing steering assembly with a reduced number of elements.
In accordance with the present invention, a shock-absorbing steering assembly comprises:
a steering shaft;
a steering column supporting said steering shaft; and
a mounting member for retaining said steering column on a vehicle body and serving to absorb an energy of an impact load relatively applied to said steering shaft in an axial direction thereof with respect to the vehicle body, wherein
said mounting member comprises:
a bracket consisting of a single element mounted to either one of said vehicle body and said steering column;
a bolt fixed to the other one of the above as engaged with said bracket; and
a collar fitted on an outer periphery of said bolt, and wherein
said bracket includes a bolt hole allowing said bolt and collar to pass therethrough in a direction intersection said axial direction, and a path continuous to said bolt hole to extend along said axial direction and smaller in width than said bolt hole, and
an edge portion of said path is a shock absorbing portion to be plastically deformed by said collar when said bracket is relatively moved along the axial direction under said impact load, said edge portion including a deformation-inducing configuration extended parallel to said path and a previously bent in section at a predetermined angle for inducing a predetermined plastic deformation according to a predetermined impact load.
In the shock-absorbing steering assembly of the above construction, the shock absorbing portion of the bracket, as a single element, absorbs the impact energy as plastically deformed by the collar on the outer periphery of the bolt. Thus is achieved the reduced number of elements involved in the shock absorption.
Also, the edge portion in the bracket absorbs the impact energy as plastically deformed by the collar on the outer periphery of the bolt. Hence, the impact energy is more readily absorbed by the bracket of a single element.
Further, one deformation-inducing configuration provides a certain plastic deformation characteristic. This permits the bracket to be designed to exhibit a predetermined shock-absorbing characteristic according to a predetermined impact load.
In this case, the deformation-inducing configuration provides the variation of the plastic deformation characteristic. This permits the bracket to be designed to exhibit a predetermined shock-absorbing characteristic according to a predetermined impact load.
In the above shock-absorbing steering assembly, the bolt hole may be defined within a bolt insertion portion formed by curving a part of the bracket, while the shock absorbing portion may be defined by a bending plate extended from an end of the bolt insertion portion along the steering column.
In this case, the bending plate unitary with the bracket absorbs the impact energy as plastically deformed by the collar on the outer periphery of the bolt. Hence, the impact energy is more readily absorbed by the bracket of a single element.
In the above shock-absorbing steering assembly, the steering column may be mounted to the vehicle body at two places thereof by means of the mounting member and another mounting member, each of the mounting members shaped like a saddle and fixed to each place with one bolt.
In this case, the steering column is mounted to the vehicle body by fixing the two mounting members to the respective places of the vehicle body using one bolt for each mounting member, thereby facilitating the mounting operation of the assembly.